The field of lubricant additives has seen a wide variety of materials used to reduce friction and wear between moving parts. Lubricants are composed principally of a base stock and a lubricant additive. The lubricant additive provides the antifriction and antiwear characteristics to the lubricant. The base stock imparts improved viscosity and thermal/oxidative stability, which can be improved by the addition of various additives. One significant advance in the field was the invention of a material called a "telomer". The telomer invention is described in U.S. Pat. No. 5,229,023, the disclosure of which is incorporated by reference herein.
Briefly, a telomer is a highly viscous polymerized triglyceride oil, principally derived from a seed oil, that has thermal oxidative stability and viscosity improvement characteristics that makes the telomer an essential component or ingredient of a large variety of lubricant formulations. The process to synthesize telomers begins with an unsaturated triglyceride oil and heats the oil in a non-oxidizing atmosphere with a trace water catalyst to lower the iodine number such that no more than 4% of the fatty acid chains of the telomer vegetable oil are polyunsaturated.
An improvement to the telomer oil was made by adding from 20% to 70% of a conjugated triglyceride oil to allow for much thicker telomer oils (i.e., higher viscosity) to be made at lower processing temperatures and times. The improvement was described in U.S. patent application Ser. No. 08/108,477 filed: 18 Aug. 1993, the disclosure of which is incorporated by reference herein. However, lower range viscosity telomer oils, (i.e., sus 5000-12,000) as prepared by the procedure described in U.S. Pat. No. 5,229,023, were still plagued by problems of too high an acid number (i.e., around 50) due to cleavage of some free fatty acids during processing and pyrolysis to raise acid numbers and cause unsuitability for use of this telomer oil in products such as hydraulic fluids and gear fluids due to oxidation and corrosion associated with the free acids.
The present invention was made in an effort to improve the telomer product by lowering temperature of formation and by improving the acid number of the telomer product such that lower range viscosity telomer oil products can be used in hydraulic fluid and gear fluid formulations without causing corrosion or oxidation problems.